Process for preparing azo dyestuffs on the fiber



Patented July 26, 1938 PATENT OFFICE PROCESS FOR PREPARING AZO DYESTUFFS ON THE FIBER Willy Tischbcin, Leverkusen-Wiesdorf, Germany, assignor to General Aniline Works, Inc., New York, N. Y., a corporation of Delaware No Drawing; Application January 27, 1937, Serial No. 122,574. In Germany February 8, 1936 7 Claims.

The present invention relates to a process for the manufacture of azo dyestuffs on the fiber.

Among the diazo compounds used for the manufacture of azo dyestuffs on the fiber there are products which .in order to attain a sufllciently great developing velocity are to be coupled .in an alkaline medium. Diazo compounds of the said kind, however, often show the disadvantage of being highly sensitive towards the addition of 10 free alkalies, and are readily decomposed and precipitated in their presence. This is partic- {ffuiarly the case, for instance, with compounds like diazotized p-methoxy-p-amino-diphenylamine, 'p-aminophenylamine, 1-amino-4-benzo- '15 ylamino-2,5-diethoxyaminobenzene or dianisidine.

Since, on the other hand, alkali is always introduced into the coupling bath by the textile material to be dyed which has been previously grounded with the coupling component in an alkaline bath, it is customary to add to the coupling bath a suitable buffer substance. As such substance which by reaction with the alkali originating from the grounding bath is maintaining in the coupling bath the desired degree of alkalinity, sodium bicarbonate, magnesium sulfate and ammonium sulfate have already been proposed. The said additions are capable, in some cases, of increasing the stability of the coupling baths to a certain degree which, however, in the case of highly sensitive diazo compounds is practically insufficient.

It is an object-of my invention to overcome these drawbacks and to increase the stability of alkaline coupling baths even of highly sensitive diazo compounds so that the said compounds will be still more useful in practical dyeing. These and other objects which will be readily recognized by those skilled in the art I attain by performing coupling of the said diazo compounds in the presence of a watersoluble salt of a noncoupling amine or organic ammonium compound.

Coupling baths prepared according to my invention are not decomposed by the alkali carried into the coupling baths by the grounding material, and they may be used for several days and for the dyeing of large quantities of material without decomposition or precipitation taking place.

I have found as the result of many experiments that the watersoluble salts of non-coupling amines and organic ammonium compounds are showing the said tendency of increasing the stability of coupling baths of the kind described.

Of course, this tendency is varying somewhat in different compounds, and it is, for instance, less in. the low molecular and strongly basic aliphatic amines .like ethyl amine and triethyl amine whereas it is stronger in the watersoluble salts 5 from less basic and/or high molecular products like triethanol amine, heterocyclic nitrogenous bases such as pyridine, piperidine, stearyl pyridinium hydroxide etc. or high molecular aliphatic nitrogenous bases like dimethyldodecyll0 ammoniumhydroxide.

The salts of the kind described may be added to the coupling bath in such quantities as are commonly used for the purpose of binding free alkali in such baths. They may also be incor- 5 porated with the diazo compound to be employed, for instance, by neutralizing the acid from the diazotizing process by means of a suitable amine or organic ammonium compound.

In order to establish from the beginning in the 20 coupling bath a definite alkaline reaction of the desired degree it may, in many cases, be desirable to add to the bath besides the said salts a certain quantity of such bases from which the salts to be employed according to my invention are derived.

Several embodiments of my invention will be furthermore illustrated by the following examples, the parts being by weight:

30 Example 1 Cotton fabrics are grounded on the foulard with an alkaline aqueous solution of 15 parts of fi-hydroxy naphthoic acid anilide in 1000 parts of water prepared in the usual way. After drying the fabrics are passed into a coupling bath containing per liter 30 parts of a salt of diazotized p-methoxy-p'-aminodiphenylamine, 2 parts of a condensation product of oleyl alcohol and ethylene oxide or of a similar dispersing agent and about 30 parts of triethanol amine sulfate.

In a similar way instead of the triethanolamine sulfate the salts of triethanolamine with hydrochloric, acetic or aminosulfonic acid may be em- 5 ployed. The same beneficient action of these products will be observed, for instance, when p-hydroxynaphthoic acid-o-anisidide is used for grounding and is coupled with diazotized l-amino-4-benzoylamino-2,5-diethoxybenzene or di- 50 methoxy-l-amino-4-benzoylamino-2 ,5-diethoxybenzene.

Example 2 50 parts of cotton skeins or mixed cotton/viscose artificial silk hanks are grounded as usual in a 55 solution containing per liter 4.5 parts of p-hydroxynaphthoic acid anilide and, after squeezing. are introduced into a coupling bath containing per liter 3.5 parts of diazotized 1-amino-4-benzoylamino-2,5-diethoxybenzene, 2 parts of a condensation product 01' oleyl alcohol and ethylene oxide and about 15 parts of the salt of dlethanol amine and amino sulfonic acid.

Example 3 Cotton goods are grounded and the dyestufl is developed as described in Example 1, but in the presence of about parts 01! piperidine hydrochloride instead of the triethanolamine salt.

Example 4 Similar results as described in the foregoing examples are obtained by adding to the coupling baths an equal amount of stearyl pyridinium acetate. i

Example 5 Cotton fabrics are grounded and developed as described in Example 1. In order'to establish from the beginning a definite alkaline pH in the coupling bath besides the trlethanolamine salt about 5 parts of free triethanolamine are added to the coupling bath.

I claim:-

1. In the process of preparing azo dyestufls on the fiber by means 01 a diazo compound which is sensitive towards alkali the modification which comprises coupling the diazo compound in alkaline solution in the presence 01 a watersoluble salt of a non-coupling base selected from the group consisting of amines and organic ammonium compounds.

2. In a process according to claim 1, coupling in the presence of a watersoluble salt of an ethanolamine.

3. In a process according to claim 1, coupling in the presence of a water-soluble salt of triethanolamine.

4. In a process according to claim 1, coupling in the presence of a watersoluble salt of a nondodecylammonium hydroxide. 

